Lens Array Apparatus

ABSTRACT

A lens array apparatus and a manufacturing method thereof are provided in which the lens array apparatus can achieve appropriate optical performance regardless of changes in ambient temperature. 
     As a predetermined angle of gradient in relation to a thickness direction for each of a plurality of lenses  11 , an exiting direction of light emitted from each lens  11  is at an angle of gradient allowing respective converging points of the light emitted from each lens  11  to be positioned on a predetermined straight line  23  that corresponds to each lens  11  and is parallel with the thickness direction, under a plurality of different ambient temperatures.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens array apparatus and amanufacturing method thereof. In particular, the present inventionrelates to a lens array apparatus including a plurality of lensesarrayed in a predetermined array direction and a manufacturing methodthereof. The lens array apparatus is suitable for allowing each lens toemit incoming light towards a predetermined converging point.

2. Description of the Related Art

Conventionally, in the field of optical fiber communication and thelike, a lens array is used in which a plurality of lenses are arrayed ina predetermined array direction.

In this type of lens array, for example, a light-emitting device inwhich a plurality of vertical cavity surface emitting lasers (VCSEL) arearrayed as light-emitting elements is disposed such that each VCSELfaces each lens. As a result, light emitted from each VCSEL enters eachlens. Each lens emits the incoming light towards a predeterminedconverging point.

Then, at the converging point, the light emitted from each lens entersan optical device disposed on a light-emission side the lens array, suchas a light-receiving device (for example, a photodetector) including anoptical fiber and a plurality of light-receiving elements.

-   Patent Literature 1: Japanese Patent Laid-open Publication No.    2004-138982

As shown in FIG. 15, in a conventional lens array 1, each VCSEL 2 of thelight-emitting device is disposed on a center axis 5 of each lens 3. Thelight emitted from each lens 3 advances in a direction perpendicular tothe array direction (horizontal direction in FIG. 15).

Therefore, when the lens array 1 is made of a material that easilyexpands due to heat, as a result of heat expansion of the lens array 1accompanying a change in ambient temperature, as shown in FIG. 15, aposition of a converging point P′ of the light emitted from each lens 3may become significantly displaced in the array direction of the lenses3 from a design position P.

When the converging point is displaced in the array direction in thisway, a problem occurs in the optical device (optical fiber 6 in FIG. 15)on the emission side of the lens array 1 in that the light emitted fromthe lens array 1 cannot be appropriately received.

SUMMARY OF THE INVENTION

Therefore, the present invention has been achieved in light of theabove-described issues. An object of the present invention is to providea lens array apparatus and a manufacturing method thereof in which thelens array apparatus can achieve appropriate optical performanceregardless of a change in ambient temperature.

In order to achieve the aforementioned object, a lens array apparatusaccording to a first aspect of the present invention includes a lensarray including a plurality of lenses formed such as to be arrayed in apredetermined array direction and formed to have a predeterminedthickness in a thickness direction that is perpendicular to the arraydirection. The lens array emits light that has entered the plurality oflenses and corresponds to each lens from each lens towards apredetermined converging point. The lens array apparatus also includes alight-emitting device that is disposed in a position facing the lensarray in the thickness direction and on which a plurality oflight-emitting elements of a same number as a number of lenses areformed. The light-emitting elements respectively emit lightcorresponding to each lens towards the plurality of lenses. In the lensarray apparatus, as a predetermined angle of gradient in relation to thethickness direction for each lens, an exiting direction of light fromeach of the plurality of lenses is at an angle of gradient allowing aconverging point of the light emitted from each lens to be positioned ona predetermined straight line that corresponds to each lens and isparallel in the thickness direction, under a plurality of ambienttemperatures.

In the first aspect of the present invention, the converging point ofthe light emitted from each lens in the lens array is formed to bepositioned on a straight line that corresponds to each lens, underdifferent ambient temperatures. Therefore, appropriate opticalperformance can be achieved, regardless of changes in the ambienttemperature.

A lens array apparatus according to a second aspect of the presentinvention is the lens array apparatus according to the first aspect, inwhich each center axis of the plurality of lenses is formed parallelwith the thickness direction. The exiting direction is at the angle ofgradient by the plurality of light-emitting elements being formed suchas to be displaced by a predetermined displacement amount in the arraydirection from each center axis of the plurality of lenses.

In the second aspect of the present invention, each light-emittingelement is formed such as to be displaced by a predetermineddisplacement amount in the array direction from the center axis of eachlens. Therefore, the converging point of the light emitted from eachlens can be positioned on the straight line corresponding to each lensunder a plurality of ambient temperatures. As a result, appropriateoptical performance can be achieved with a simple configuration,regardless of changes in the ambient temperature.

A lens array apparatus according to a third aspect of the presentinvention is the lens array apparatus according to the first aspect, inwhich each of the plurality of lenses has a lens surface on alight-entering side facing the light-emitting element and a lens surfaceon a light-exiting side opposing the lens surface on the light-enteringside. The exiting direction is at the angle of gradient by each of theplurality of lenses being formed such that a predetermined displacementamount in the array direction is present between a center axis of thelens surface on the light-entering side and a center axis of the lenssurface on the light-exiting side.

In the third aspect of the present invention, a predetermineddisplacement amount in the array direction is present between the centeraxis of the lens surface on the light-entering side and the center axisof the lens surface on the light-exiting side for each lens. Therefore,the converging point of the light emitted from each lens can bepositioned on the straight line corresponding to each lens under aplurality of ambient temperatures. As a result, appropriate opticalperformance can be achieved with a simple configuration, regardless ofchanges in the ambient temperature.

A lens array apparatus according to a fourth aspect of the presentinvention is the lens array apparatus according to the first aspect, inwhich the exiting direction is at the angle of gradient by each centeraxis of the plurality of lenses being formed at the angle of gradient inrelation to the thickness direction.

In the fourth aspect of the present invention, the center axis of eachlens is formed at the angle of gradient in relation to the thicknessdirection. Therefore, the converging point of the light emitted fromeach lens can be positioned on the straight line corresponding to eachlens under a plurality of ambient temperatures. As a result, appropriateoptical performance can be achieved with a simple configuration,regardless of changes in the ambient temperature.

A lens array apparatus according to a fifth aspect of the presentinvention is the lens array apparatus according to any one of the firstto fourth aspects, in which a light-receiving device is disposed in aposition on a light-exiting side of the lens array. The light-exitingside is a side from which light from the plurality of lenses exits. Thelight-receiving device includes a plurality of optical fibers of a samenumber as a number of lenses into which light emitted from each lensrespectively enters. Alternatively, the light-receiving device includesa plurality of light-receiving elements of a same number as a number oflenses that receive light emitted from each lens.

In the fifth aspect of the present invention, the light emitted from thelight-emitting elements can be appropriately coupled with the opticalfibers or the light-receiving elements, regardless of changes in theambient temperature.

A manufacturing method for a lens array apparatus according to a sixthaspect of the present invention is a manufacturing method for a lensarray apparatus that includes a lens array including a plurality oflenses formed such as to be arrayed in a predetermined array directionand formed to have a predetermined thickness in a thickness directionthat is perpendicular to the array direction. The lens array emits lightthat has entered the plurality of lenses and corresponds to each lensfrom each lens towards a predetermined converging point. The lens arrayapparatus also includes a light-emitting device that is disposed in aposition facing the lens array in the thickness direction and on which aplurality of light-emitting elements of a same number as a number oflenses are formed. The light-emitting elements respectively emit lightcorresponding to each lens towards the plurality of lenses. In themanufacturing method for a lens array apparatus, as a predeterminedangle of gradient in relation to the thickness direction for each lens,an exiting direction of light from each of the plurality of lenses is atan angle of gradient allowing a converging point of the light emittedfrom each lens to be positioned on a predetermined straight line thatcorresponds to each lens and is parallel in the thickness direction,under a plurality of different ambient temperatures.

In the sixth aspect of the present invention, the converging point ofthe light emitted from each lens in the lens array is positioned on astraight line that corresponds to each lens, under different ambienttemperatures. Therefore, the lens array apparatus can achieveappropriate optical performance regardless of changes in the ambienttemperature.

A manufacturing method for a lens array apparatus according to a seventhaspect of the present invention is a manufacturing method for a lensarray apparatus according to the sixth aspect, in which each center axisof the plurality of lenses is formed parallel with the thicknessdirection. The exiting direction is at the angle of gradient by theplurality of light-emitting elements being formed such as to bedisplaced by a predetermined displacement amount in the array directionfrom each center axis of the plurality of lenses.

In the seventh aspect of the present invention, each light-emittingelement is formed such as to be displaced by a predetermineddisplacement amount in the array direction from the center axis of eachlens. Therefore, the converging point of the light emitted from eachlens can be positioned on the straight line corresponding to each lensunder a plurality of ambient temperatures. As a result, the lens arrayapparatus can achieve appropriate optical performance with a simpleconfiguration, regardless of changes in the ambient temperature.

A manufacturing method for a lens array apparatus according to an eighthaspect of the present invention is a manufacturing method for a lensarray apparatus according to the seventh aspect, in which, from acoefficient of temperature dependence of refractive index andcoefficient of linear expansion of a material forming the lens array, anamount of change in the thickness direction of a position of eachconverging point of the plurality of lenses accompanying a predeterminedtemperature change and an amount of change in a distance of each centeraxis of the plurality of lenses from a reference surface of the lensarray accompanying the predetermined temperature change are determined.The reference surface is perpendicular to the array direction. For eachof the plurality of lenses, a right triangle is assumed of which twosides are a first side that is parallel with the thickness direction andhas a length equivalent to the amount of change in the position of theconverging point and a second side that is parallel with the arraydirection and has a length equivalent to the amount of change in thedistance of the center axis. An angle formed by a hypotenuse of theright triangle and the thickness direction is determined for each lens.A displacement amount is determined for each of the plurality oflight-emitting elements corresponding to each lens. The displacementamount allows an exiting direction of the light from each of theplurality of lenses to be at the angle determined for each lens inrelation to the thickness direction, towards a direction in the arraydirection counter to a heat expansion direction of the lens array. Eachlight-emitting element is disposed such as to be displaced by thedetermined displacement amount.

In the eighth embodiment of the present invention, each light-emittingelement can be accurately displaced by a predetermined displacementamount in the array direction from the center axis of each lens.Therefore, optical performance can be enhanced, and cost can be reduced.

A manufacturing method for a lens array apparatus according to a ninthaspect of the present invention is a manufacturing method for a lensarray apparatus according to the sixth aspect, in which each of theplurality of lenses has a lens surface on a light-entering side facingthe light-emitting element and a lens surface on a light-exiting sideopposing the lens surface on the light-entering side. The exitingdirection is at the angle of gradient by each of the plurality of lensesbeing formed such that a predetermined displacement amount in the arraydirection is present between a center axis of the lens surface on thelight-entering side and a center axis of the lens surface on thelight-exiting side.

In the ninth aspect of the present invention, a predetermineddisplacement amount in the array direction is present between the centeraxis of the lens surface on the light-entering side and the center axisof the lens surface on the light-exiting side for each lens. Therefore,the converging point of the light emitted from each lens can bepositioned on the straight line corresponding to each lens under aplurality of ambient temperatures. As a result, the lens array apparatuscan achieve appropriate optical performance through use of a simplemethod, regardless of changes in the ambient temperature.

A manufacturing method for a lens array apparatus according to a tenthaspect of the present invention is a manufacturing method for a lensarray apparatus according to the ninth aspect, in which a design lensarray is assumed that is used to design the lens array in which apredetermined displacement amount is present between the center axis ofthe lens surface on the light-entering side and the center axis of thelens surface on the light-exiting side. The design lens array is made ofa same material as that of the lens array. The design lens arrayincludes a plurality of lenses arrayed in a predetermined arraydirection and having a predetermined thickness in a thickness directionthat is perpendicular to the array direction. In the design lens array,the center axis of the lens surface on the light-entering side and thecenter axis of the lens surface on the light-exiting side of each lensmatch. From a coefficient of temperature dependence of refractive indexand coefficient of linear expansion of the material forming the assumeddesign lens array, an amount of change in the thickness direction of aposition of each converging point of the plurality of lenses in thedesign lens array accompanying a predetermined temperature change and anamount of change in a distance of each center axis of the plurality oflenses from a reference surface of the design lens array accompanyingthe predetermined temperature change are determined. The referencesurface is perpendicular to the array direction. For each of theplurality of lenses in the design lens array, a right triangle isassumed of which two sides are a first side that is parallel with thethickness direction and has a length equivalent to the amount of changein the position of the converging point and a second side that isparallel with the array direction and has a length equivalent to theamount of change in the distance of the center axis. An angle formed bya hypotenuse of the right triangle and the thickness direction isdetermined for each lens. A displacement amount is determined for eachlens. The displacement amount allows an exiting direction of the lightfrom each of the plurality of lenses in the design lens array to be atthe angle determined for each lens in relation to the thicknessdirection, towards a direction in the array direction counter to a heatexpansion direction of the lens array. A positional relationship betweenthe center axis of the lens surface on the light-entering side and thecenter axis of the lens surface on the light-exiting side in the designlens array is adjusted to have the determined displacement amount. As aresult, the lens array having the displacement amount between the centeraxis of the lens surface on the light-entering side and the center axisof the lens surface on the light-exiting side is designed. The lensarray is formed based on a design result.

In the tenth aspect of the present invention, a predetermineddisplacement amount in the array direction is accurately present betweenthe center axis of the lens surface on the light-entering side and thecenter axis of the lens surface on the light-exiting side of each lens,through use of a simple method. Therefore, optical performance can befurther enhanced, and cost can be reduced.

A manufacturing method for a lens array apparatus according to aneleventh aspect of the present invention is a manufacturing method for alens array apparatus according to the sixth aspect, in which the exitingdirection is at the angle of gradient by each center axis of theplurality of lenses being formed at the angle of gradient in relation tothe thickness direction.

In the eleventh aspect of the present invention, the center axis of eachlens is at the angle of gradient in relation to the thickness direction.Therefore, the converging point of the light emitted from each lens canbe positioned on the straight line corresponding to each lens under aplurality of ambient temperatures. As a result, the lens array apparatuscan achieve appropriate optical performance through use of a simplemethod, regardless of changes in the ambient temperature.

A manufacturing method for a lens array apparatus according to a twelfthaspect of the present invention is a manufacturing method for a lensarray apparatus according to the eleventh aspect, in which a design lensarray is assumed that is used to design the lens array in which thecenter axis is at the angle of gradient in relation to the thicknessdirection. The design lens array is made of a same material as that ofthe lens array. The design lens array includes a plurality of lensesarrayed in a predetermined array direction and having a predeterminedthickness in a thickness direction that is perpendicular to the arraydirection. In the design array, the center axis of each lens is parallelwith the thickness direction. From a coefficient of temperaturedependence of refractive index and coefficient of linear expansion ofthe material forming the assumed design lens array, an amount of changein the thickness direction of a position of each converging point of theplurality of lenses in the design lens array accompanying apredetermined temperature change and an amount of change in a distanceof each center axis of the plurality of lenses from a reference surfaceof the design lens array accompanying the predetermined temperaturechange are determined. The reference surface is perpendicular to thearray direction. For each of the plurality of lenses in the design lensarray, a right triangle is assumed of which two sides are a first sidethat is parallel with the thickness direction and has a lengthequivalent to the amount of change in the position of the convergingpoint and a second side that is parallel with the array direction andhas a length equivalent to the amount of change in the distance of thecenter axis. An angle formed by a hypotenuse of the right triangle andthe thickness direction is determined for each lens as the angle ofgradient. An angle of each center axis of the plurality of lenses in thedesign lens array is adjusted to allow an exiting direction of the lightfrom each of the plurality of lenses in the design lens array to be atthe angle of gradient determined for each lens in relation to thethickness direction, towards a direction in the array direction counterto a heat expansion direction of the lens array. As a result, the lensarray in which the center axis is at the angle of gradient in relationto the thickness direction is designed. The lens array is formed basedon a design result.

In the twelfth aspect of the present invention, the center axis of eachlens can accurately be at a predetermined angle of gradient in relationto the thickness direction. Therefore, optical performance can befurther enhanced, and cost can be reduced.

A manufacturing method for a lens array apparatus according to athirteenth aspect of the present invention is a manufacturing method fora lens array apparatus according to any one of sixth to twelfth aspects,in which a light-receiving device is disposed in a position on alight-exiting side of the lens array. The light-exiting side is a sidefrom which light from the plurality of lenses exits. The light-receivingdevice includes a plurality of optical fibers of a same number as anumber of lenses into which light emitted from each lens respectivelyenters. Alternatively, the light-receiving device includes a pluralityof light-receiving elements of a same number as a number of lenses thatreceive light emitted from each lens.

In the thirteenth aspect of the present invention, the light emittedfrom the light-emitting elements can be appropriately coupled with theoptical fibers or the light-receiving elements regardless of changes inthe ambient temperature.

Effect of the Invention

In the lens array apparatus and the manufacturing method thereof of thepresent invention, appropriate optical performance can be achievedregardless of changes in ambient temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram of a lens array apparatus according toa first embodiment of the present invention;

FIG. 2 is a planar view of a lens array in the lens array apparatusaccording to the first embodiment of the present invention;

FIG. 3 is a vertical cross-sectional view of the lens array in the lensarray apparatus according to the first embodiment of the presentinvention;

FIG. 4 is an explanatory diagram of main components of the lens arrayapparatus according to the first embodiment of the present invention;

FIG. 5 is a vertical cross-sectional view of an aspect of the lens arraydiffering from that in FIG. 2;

FIG. 6 is an explanatory diagram of procedures performed to prepare adesign lens array apparatus in a manufacturing method of the lens arrayapparatus according to the first embodiment of the present invention;

FIG. 7 is an explanatory diagram of a procedure performed to simulatedisplacement of a center axis and a converging point accompanying heatexpansion in the manufacturing method of the lens array apparatusaccording to the first embodiment of the present invention;

FIG. 8 is an explanatory diagram of a procedure performed to calculatean angle of gradient obtained from the simulation in FIG. 7 in themanufacturing method of the lens array apparatus according to the firstembodiment of the present invention;

FIG. 9 is an explanatory diagram of a procedure performed to defineoutgoing light in the manufacturing method of the lens array apparatusaccording to the first embodiment of the present invention;

FIG. 10 is an explanatory diagram of a procedure performed to determinedisplacement of a light-emitting section in the manufacturing method ofthe lens array apparatus according to the first embodiment of thepresent invention;

FIG. 11 is an explanatory diagram of main components of a lens arrayapparatus according to a second embodiment of the present invention;

FIG. 12 is an explanatory diagram of a procedure performed to determinedisplacement of a center axis of a lens surface in a manufacturingmethod of the lens array apparatus according to the second embodiment ofthe present invention;

FIG. 13 is an explanatory diagram of main components of a lens arrayapparatus according to a third embodiment of the present invention;

FIG. 14 is an explanatory diagram of a procedure performed to adjust anangle of a center axis of a lens surface in a manufacturing method ofthe lens array apparatus according to the third embodiment of thepresent invention; and

FIG. 15 is a configuration diagram of an example of a conventional lensarray apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT First Embodiment

A lens array apparatus and a manufacturing method thereof according to afirst embodiment of the present invention will be described withreference to FIG. 1 to FIG. 10.

(Configuration of the Lens Array Apparatus)

As shown in FIG. 1, a lens array apparatus 7 according to the firstembodiment includes a lens array 8 and a light-emitting device 10attached to the lens array 8.

The lens array 8 is described in further detail as follows. As shown ina planar view in FIG. 2, the lens array 8 includes a plate-shaped lensforming section 8 a having a roughly rectangular planar shape and aframe section 8 b surrounding the lens forming section 8 a in fourdirections. The frame section 8 b is thicker than the lens formingsection 8 a. More specifically, as shown in FIG. 1 and FIG. 3, both endsurfaces (top end surface and bottom end surface in FIG. 3) of the framesection 8 b in the thickness direction are positioned on outer sides ofthe lens forming section 8 a in the thickness direction.

As shown in FIG. 1 to FIG. 3, a plurality of lenses 11 (12 lenses inFIG. 1 to FIG. 3) are formed in the lens forming section 8 a, arrayedalong a horizontal direction in FIG. 1 to FIG. 3 that is a predeterminedarray direction.

Each lens 11 has a predetermined thickness in the thickness direction(vertical direction in FIG. 1 and FIG. 3) perpendicular to the arraydirection. A lens surface 11 a on a light-entering side facing thelight-emitting device 10 and a lens surface 11 b on a light-exiting sideopposing the lens surface 11 a in the thickness direction have a commoncenter axis 12. In other words, the center axis 12 of the lens surface11 a and the center axis 12 of the lens surface 11 b match. The centeraxis 12 is parallel with the thickness direction. The lens 11 accordingto the first embodiment is a bi-convex lens having a circular planarshape.

Light emitted from the light-emitting device 10 and corresponding toeach lens 11 enters each lens 11 via the lens surface 11 a on thelight-entering side. The light entering each lens 11 is emitted from thelens surface 11 b on the light-exiting side towards a predeterminedconverging point corresponding to each lens 11.

A pair of hole sections 14 penetrating the frame section 8 b in thethickness direction are formed on the frame section 8 b. The holesections 14 are used to position the light-emitting device 10 when thelight-emitting device 10 is attached to the lens array 8 and to positionan optical fiber 19 when the optical fiber 19, described hereafter, isattached to the lens array 8.

A lens array 8 such as this can be integrally formed by an efficientmanufacturing method using an inexpensive material, such asinjection-molding of a resin material using a mold.

As shown in FIG. 1, the light-emitting device 10 includes a flatsemiconductor substrate 15. A same number of vertical cavity surfaceemitting lasers (VCSEL) 16 as the number of lenses 11 are formed on asurface of the semiconductor substrate 15 that faces the lens array 8,along the array direction of the lenses 11. The VCSEL 16 serves as alight-emitting element. Each VCSEL 16 emits light corresponding to eachlens 11 towards a corresponding lens 11.

A pair of projection sections 18 are disposed on the semiconductorsubstrate 15 in positions facing the pair of hole sections 14 on thelens array 8. The projection sections 18 project towards the lens array8 side in a thickness direction of the semiconductor substrate 15. Theprojection sections 18 respectively engage with the hole sections 14 ofthe lens array 8. As a result, the projection sections 18 are used toposition the light-emitting device 10 when the light-emitting device 10is attached to the lens array 8.

Moreover, as shown in FIG. 1, when the light-emitting device 10 isattached to the lens array 8, the surface of the semiconductor substrate15 facing the lens array 8 is in contact with an end surface of theframe section 8 b facing the light-emitting device 10. Thelight-emitting device 10 is disposed in a position facing the lens array8 in the thickness direction.

On the other hand, as shown in FIG. 1, according to the embodiment, asame number of optical fibers 19 as the number of lenses 11 are attachedto positions on the light-exiting side of the lens array 8 from whichlight exit the lenses 11. The optical fibers 19 are arrayed along thearray direction of the lenses 11. A portion on an end section side ofeach optical fiber 19 in FIG. 1 is held within a multi-core bundledconnector 20.

Light emitted from the lens surface 11 b on the light-exiting side ofthe lens array 8 enters each end surface 19 a of the optical fibers 19.Each optical fiber 19 transmits the light entering from the lens array 8side to a transmitting destination.

A pair of projection sections 21 that are long in the thicknessdirection in FIG. 1 are disposed in positions on the connector 20 facingthe pair of hole sections 14 of the lens array 8. The projectionsections 21 respectively engage with the hole sections 14 in the lensarray 8. As a result, the projection sections 21 are used to positionthe optical fibers 19 when the optical fibers 19 are attached to thelens array 8.

In this way, the lens array 8 according to the first embodiment canoptically couple the plurality of VCSEL 16 in the light-emitting device10 and the respective end surfaces 19 a of the plurality of opticalfibers 19 corresponding to each VCSEL 16.

The lens array apparatus 7 according to the first embodiment has a basicconfiguration such as that described above. In the lens array apparatus7, as a predetermined angle of gradient in relation to the thicknessdirection for each lens 11, an exiting direction of the light emittedfrom each lens 11 is at an angle of gradient allowing respectiveconverging points of the light emitted from each lens 11 to bepositioned on a predetermined straight line 23 that corresponds to eachlens 11 and is parallel with the thickness direction, under a pluralityof different ambient temperatures.

Moreover, according to the first embodiment, the angles of gradient inrelation to the thickness direction regarding the exiting direction ofthe light emitted from each lens 11 such as these are actualized becauseeach VCSEL 16 is displaced in the array direction from the center axis12 of each lens 11 corresponding to each VCSEL 16 by a predeterminedamount.

FIG. 4 is a detailed diagram of a configuration of the lens arrayapparatus 7 according to the first embodiment, as described above, inwhich focus is placed only on a corresponding set of lens 11, VCSEL 16,and optical fiber 19, to simplify explanation.

As shown in FIG. 4, the lens array apparatus 7 according to theembodiment is formed such that, when the ambient temperature of the lensarray apparatus 7 is a normal temperature (T₁[° C.] in FIG. 4), servingas a predetermined ambient temperature, the VCSEL 16 is formed (placed)such as to be displaced in the array direction from the center axis 12(under the normal temperature T₁) of the lens 11 by a predetermineddisplacement amount Δd[mm] in a heat expansion direction (to the rightin FIG. 4) of the lens array 8. A specific normal temperature can bevariably selected based on concept. In the lens array 8 according to thefirst embodiment, the heat expansion direction is a direction from acenter section of the lens array 8 in the array direction towards bothend sections on the left and the right.

As a result, when the ambient temperature of the lens array apparatus 7is the normal temperature (T₁[° C.] in FIG. 4), after the light emittedfrom the VCSEL 16 passes through the lens 11 corresponding to the VCSEL16 and the light is emitted towards a converging point P1 as an outgoinglight L₁ from the lens surface 11 b on the light-exiting side of thelens 11, the exiting direction of the outgoing light L₁ is at an angleof gradient A in relation to the thickness direction.

Then, when the ambient temperature changes from the normal temperatureto a high temperature (T₂[° C.] in FIG. 4, where T₂>T₁) the lens array 8expands in the heat expansion direction (to the right in FIG. 4) as aresult of heat expansion reflecting a coefficient of linear expansion aof the material. As a result, a diameter of the lens 11 increases andthe center axis 12 is displaced in the heat expansion direction.According to the first embodiment, the coefficient of linear expansionof the material forming the semiconductor substrate 15 is the same asthe coefficient of linear expansion a of the material forming the lensarray 8. Therefore, according to the first embodiment, when the lens 11is displaced in accompaniment with the heat expansion of the lens array8, the VCSEL 16 formed on the semiconductor substrate 15 is displaced byalmost the same displacement amount in the same direction as the lens 11in accompaniment with the heat expansion of the semiconductor substrate15.

When the ambient temperature becomes a high temperature in this way, thelight emitted from the VCSEL 16 passes through the lens 11 (the lens 11under the high temperature) that has undergone heat expansion from astate under the normal temperature and is then emitted towards aconverging point P₂ under the high temperature, as an outgoing light L₂under the high temperature, from the lens surface 11 b on thelight-exiting side (under the high temperature T₂).

At this time, the exiting direction of the outgoing light L₂ under thehigh temperature is at the angle of gradient θ in relation to thethickness direction, similar to the outgoing light L₁ under the normaltemperature.

At this time, the converging point P₂ under the high temperature isfarther away from the lens surface 11 b than the converging point P₁under the normal temperature because of the effect of coefficient oftemperature dependence of refractive index dn/dT of the material formingthe lens array 8.

As a result, as shown in FIG. 4, the converging point P₁ under thenormal temperature and the converging point P₂ under the hightemperature are positioned on a straight line 23 that is parallel withthe thickness direction.

Therefore, as shown in FIG. 4, when the optical fiber 19 is formed suchthat the center of the end surface 19 a of the optical fiber 19 ispositioned on the straight line 23, the light emitted from the VCSEL 16can be appropriately coupled with the optical fiber 19, regardless ofwhether the ambient temperature is the normal temperature or the hightemperature. The converging point P₂ under the high temperature isdisplaced in the thickness direction from the end surface 19 a of theoptical fiber 19. However, displacement, such as this, in the thicknessdirection has significantly less influence on optical performancecompared to when the converging point P₂ under the high temperature ismisaligned in the array direction with the converging point P₁ under thenormal temperature. The displacement in the thickness direction issufficiently allowable under practice.

In FIG. 4, two ambient temperatures, the normal temperature and the hightemperature, are given as the ambient temperatures. However, even undera predetermined low temperature (such as T₃[° C.]) that is lower thanthe normal temperature, the converging point of the outgoing light fromthe lens surface 11 b can be positioned on the straight line 23. Basedon the lens 11 under the normal temperature, the diameter of the lens 11under the low temperature decreases as a result of heat contraction fromthe state under the normal temperature. The center axis 12 is displacedin a direction (to the left in FIG. 4) counter to the heat expansiondirection from the state under the normal temperature. Even underambient temperatures other than the normal temperature T₁[° C.], thehigh temperature T₂[° C.], and the low temperature T₃[° C.], theconverging point of the outgoing light from the lens 11 under eachambient temperature can be positioned on the straight line 23.Furthermore, a trajectory of the converging points of the outgoing lightfrom each lens 11 accompanying the change in ambient temperature of thelens array apparatus 7 can form a line segment on the straight line 23that is parallel to the thickness direction and corresponds to each lens11.

Therefore, according to the first embodiment, the converging point ofthe outgoing light from each lens 11 in the lens array 8 can bepositioned on the straight line 23 corresponding to each lens 11 under aplurality of ambient temperatures. Therefore, regardless of changes inthe ambient temperature (such as from the normal temperature T₁[° C.] tothe high temperature T₂[° C.], the VCSEL 16 and the optical fiber 19 canbe appropriately coupled.

Moreover, the lens array apparatus 7 that can perform an appropriateoptical coupling such as this can be actualized at a low cost with asimple configuration in which the position of the VCSEL 16 is displacedin the array direction from the center axis 12 of the lens 11.

Instead of the lens array 8 shown in FIG. 1 to FIG. 3, a lens array 25including plano-convex lenses 24 shown in FIG. 5 can be used. In thisinstance, whether to place the VCSEL 16 such as to face the planarsurface or the convex surface of the lenses 24 can be variably changedbased on the concept.

(Manufacturing Method of the Lens Array Apparatus)

To manufacture the lens array apparatus according to the firstembodiment, first, as shown in FIG. 6, as a lens array apparatus fordesign used to design the lens array apparatus 7 according the firstembodiment, a lens array apparatus 27 is prepared as a design lens arrayapparatus 27 used for designing the lens array apparatus 7 according tothe first embodiment. In the lens array apparatus 27, the VCSEL 16 ofthe light-emitting device 10 are respectively formed on the center axes12 of the lenses 11 in the lens array 8. The lens array apparatus 27 canbe a design assumption.

At this time, the coefficient of linear expansion a and the coefficientof linear dependence of refractive index dn/dT of the material used toform the lens array 8 in the design lens array apparatus 27 are grasped.

Next, under the normal temperature T₁[° C.] serving as the predeterminedambient temperature, a distance L[mm] in the array direction from areference surface S to the center axis 12 is measured for each lens 11(only one lens is shown in FIG. 6 to simplify explanation). Thereference surface S is a surface taken from the lens array 8 that isperpendicular to the array direction. The reference surface S can alsobe taken from a center section of the lens array 8 in the arraydirection.

At this time, through simulation, a converging point P₁′ of the outgoinglight from each lens 11 regarding the light entering each lens 11 fromeach VCSEL 16 is determined. In FIG. 6, the position of the convergingpoint P₁′ is indicated as a focal distance F[mm] on the optical fiber 19side of the lens 11. In FIG. 6, the converging point P₁′ is positionedat a center point of the end surface 19 a of the optical fiber 19.

Next, in the design lens array apparatus 27, it is assumed that theambient temperature has changed from the normal temperature T₁[° C.] tothe high temperature T₂[° C.], as shown in FIG. 7.

At this time, as shown in FIG. 7, an amount of change ΔL[mm] in thedistance in the array direction between the reference surface S and thecenter axis 12 of the lens 11 accompanying the change in temperaturefrom the normal temperature (T₂−T₁) is determined for each lens 11. Theamount of change ΔL[mm] can be determined based on the coefficient oflinear expansion a of the material forming the lens array 8.

In addition, at this time, as shown in FIG. 7, an amount of change inthe position of the converging point of the lens 11 accompanying thechange in temperature from the normal temperature (T₂−T₁) is determinedfor each lens 11. In FIG. 7, the converging point changes from P₁′ toP₂′ as a result of the change in temperature from the normaltemperature. However, the change in the position of the converging pointis determined as an amount of change ΔF[mm] in the focal distance.

Next, as shown in FIG. 8, regarding each lens 11, a right triangle isassumed of which two sides are a first side A and a second side B. Thefirst side A is parallel with the thickness direction and has a lengthequivalent to the amount of change ΔF[mm] in the position of theconverging point. The second side B is parallel with the array directionand has a length equivalent to the amount of change ΔL[mm] in thedistance of the center axis 12 of the lens 11. An angle formed by ahypotenuse C of the right triangle and the thickness direction isdetermined for each lens 11.

Next, as shown in FIG. 9, the following is defined as the outgoing lightL₁ from each lens 11. The exiting direction of the outgoing light L₁ isat an angle θ (in other words, the angle of gradient), determined inFIG. 8 for each lens 11, in relation to the thickness direction, towardsthe direction (to the left in FIG. 9) in the array direction counter tothe heat expansion direction of the lens array 8. The outgoing light L₁can also be defined as light of which the center axis passes through acenter of curvature of the lens 11 b on the light-exiting side. Theoutgoing light L₁ is equivalent to the outgoing light L₁ under thenormal temperature of the lens array apparatus 7 shown in FIG. 4.

Next, as shown in FIG. 10, as a physical amount specifying the positionof the VCSEL 16 that can emit the outgoing light L₁ defined in FIG. 9, adisplacement amount [mm] of the VCSEL in the array direction from thecenter axis 12 of the lens 11 is determined. The displacement amount canbe calculated by simulation. Alternatively, with β as the magnificationof the lens 11, the displacement amount can be approximated by β×ΔL.When the displacement amount is determined by β×ΔL, the displacementamount is ΔL[mm] when the lens 11 is magnified by one.

The lens array apparatus 7 according to the first embodiment, shown inFIG. 4, can be manufactured as a result of the lens array apparatus 7being designed such that each VCSEL 16 is arranged to be displaced bythe displacement amount Δd, determined as described above, and thecenter section of the end surface 19 a of the optical fiber 19 matchesthe converging point P₁ of the outgoing light L₁.

Second Embodiment

A lens array apparatus and a manufacturing method thereof according to asecond embodiment of the present invention will be described withreference to FIG. 11 and FIG. 12.

Sections of which the basic configuration is the same as or similar tothat according to the first embodiment are explained using the samereference numbers.

(Configuration of the Lens Array Apparatus)

FIG. 11 is a detailed diagram similar to FIG. 4, in which focus isplaced only on a corresponding set of lens 11, VCSEL 16, and opticalfiber 19 as main components of a lens array apparatus 29 according tothe second embodiment. The configuration shown in FIG. 11 applies to allsets of lens 11, VCSEL 16, and optical fiber 19.

As shown in FIG. 11, the lens array apparatus 29 according to the secondembodiment is similar to that according to the first embodiment in that,as a predetermined angle of gradient in relation to the thicknessdirection, an exiting direction of the light (L₁ and L₂ in FIG. 11)emitted from the lens 11 in a lens array 31 is at an angle of gradientθ[°] allowing converging points (P₁ and P₂ in FIG. 11) of the outgoinglight to be positioned on the predetermined straight line 23 that isparallel with the thickness direction, under a plurality of differentambient temperatures (T₁ and T₂ [° C.] in FIG. 11).

However, the lens array apparatus 29 according to the second embodimentslightly differs from that according to the first embodiment regarding afurther detailed means of actualizing the angle of gradient θ[°] of theexiting direction of the outgoing light described above.

In other words, according to the second embodiment, as shown in FIG. 11,the lens array apparatus 29 is formed such that the exiting direction ofthe outgoing light is at the angle of gradient θ[°] by being formed suchthat a predetermined displacement amount Δd[mm] in the array directionis present between a center axis 12 a of the lens surface 11 a on thelight-entering side and a center axis 12 b of the lens surface 11 b onthe light-exiting side. In FIG. 11, the VCSEL 16 is positioned on thecenter axis 11 b of the lens surface 11 b on the light-exiting side. Thecenter axis 11 a of the lens surface 11 a on the light-entering side isdisplaced to the left (the direction counter to the heat expansiondirection) in the array direction by the displacement amount Δd from theVCSEL 16.

As shown in FIG. 11, even in the lens array apparatus 29 according tothe second embodiment, configured as described above, the convergingpoints P₁ and P₂ of the outgoing light L₁ and L₂ from the lens 11 can bepositioned on the predetermined straight line 23 that is parallel withthe thickness direction, under a plurality of ambient temperatures, suchas the normal temperature (T₁[° C.]) and the high temperature (T₂[°C.]).

Therefore, according to the second embodiment as well, the convergingpoint of the outgoing light from each lens 11 in the lens array 31 canbe positioned on the straight line 23 corresponding to each lens 11,under a plurality of ambient temperatures. The VCSEL 16 and the opticalfiber 19 can be appropriately optically coupled, regardless of thechange in ambient temperature.

Other configurations are similar to those according to the firstembodiment. Explanations thereof are omitted.

(Manufacturing Method of the Lens Array Apparatus)

To manufacture the lens array apparatus 29 according to the secondembodiment, as shown in FIG. 6, a design lens array apparatus 27 similarto that according to the first embodiment is presumed. In other words,the lens array apparatus 27 is presumed including a design lens array 8in which the center axis 12 of the lens surface 11 a on thelight-entering side and the center axis 12 of the lens surface 11 b onthe light-exiting side match.

After procedures shown in FIG. 6 to FIG. 9 are performed on the designlens array apparatus 27 such as that described above, as shown in FIG.12, the displacement amount Δd of the center axis having a predetermineddisplacement amount [mm] allowing the angle θ[°] determined by theprocedure in FIG. 9 is determined. According to the second embodiment,as the displacement amount Δd of the center axis, the displacementamount Δd of the center axis 12 a of the lens surface 11 a on thelight-entering side in the array direction from the center axis 12 inthe design lens array 8 is determined.

The displacement amount Ad according to the second embodiment can alsobe approximated by β×ΔL as according to the first embodiment.

The lens array 31 according to the second embodiment in which thedisplacement amount Δd is present between the center axes of the lenssurface 11 a and the lens surface 11 b is designed by the positionalrelationship between the center axis 12 of the lens surface 11 a on thelight-entering side and the center axis 12 of the lens surface 11 b onthe light-exiting side in the design lens array 8 being adjusted. Thelens array apparatus 29 according to the second embodiment ismanufactured by the lens array 31 being formed in adherence to thedesign result.

Third Embodiment

A lens array apparatus and a manufacturing method thereof according to athird embodiment of the present invention will be described withreference to FIG. 13 and FIG. 14.

Sections of which the basic configuration is the same as or similar tothat according to the first embodiment are explained using the samereference numbers.

(Configuration of the Lens Array Apparatus)

FIG. 13 is a detailed diagram similar to FIG. 4, in which focus isplaced only on a corresponding set of lens 11, VCSEL 16, and opticalfiber 19 as main components of a lens array apparatus 33 according tothe third embodiment. The configuration shown in FIG. 13 applies to allsets of lens 11, VCSEL 16, and optical fiber 19.

As shown in FIG. 13, the lens array apparatus 33 according to the thirdembodiment is similar to those according to the first embodiment and thesecond embodiment in that, as a predetermined angle of gradient inrelation to the thickness direction, an exiting direction of the light(L₁ and L₂ in FIG. 13) emitted from the lens 11 in a lens array 34 is atan angle of gradient θ[°] allowing converging points (P₁ and P₂ in FIG.13) of the outgoing light to be positioned on the predetermined straightline 23 that is parallel with the thickness direction, under a pluralityof different ambient temperatures (T₁ and T₂ [° C.] in FIG. 13).

However, the lens array apparatus 33 according to the third embodimentslightly differs from those according to the first embodiment and thesecond embodiment regarding a further detailed means of actualizing theangle of gradient θ[°] of the exiting direction of the outgoing lightdescribed above.

In other words, according to the third embodiment, as shown in FIG. 13,the center axis 12 of the lens 11 is at an angle of gradient θ[°] inrelation to the thickness direction.

As shown in FIG. 13, even in the lens array apparatus 33 according tothe third embodiment, configured as described above, the convergingpoints P₁ and P₂ of the outgoing light L₁ and L₂ from the lens 11 can bepositioned on the predetermined straight line 23 that is parallel withthe thickness direction, under a plurality of ambient temperatures, suchas the normal temperature (T₁[° C.]) and the high temperature (T₂[°C.]).

Therefore, according to the third embodiment as well, the convergingpoint of the outgoing light from each lens 11 in the lens array 34 canbe positioned on the straight line 23 corresponding to each lens 11,under a plurality of ambient temperatures. The VCSEL 16 and the opticalfiber 19 can be appropriately optically coupled, regardless of thechange in ambient temperature.

Other configurations are similar to those according to the firstembodiment. Explanations thereof are omitted.

(Manufacturing Method of the Lens Array Apparatus)

To manufacture the lens array apparatus 33 according to the thirdembodiment, as shown in FIG. 6, a design lens array apparatus 27 similarto that according to the first embodiment is presumed. In other words,the lens array apparatus 27 is presumed including a design lens array 8in which the center axis 12 of the lens 11 is parallel with thethickness direction.

After procedures shown in FIG. 6 to FIG. 9 are performed on the designlens array apparatus 27 such as that described above, as shown in FIG.14, the lens array 34 according to the third embodiment is designed bythe angle of the center axis 12 of the lens 11 in relation to thethickness direction being adjusted such that the center axis 12 of thelens 11 is at an the angle θ[°] determined by the procedure in FIG. 9.The lens array apparatus 34 according to the third embodiment ismanufactured by the lens array 34 being formed in adherence to thedesign result.

As described above, the present invention is configured such that theconverging point of light emitted from each lens 11 in the lens array 8,the lens array 31, and the lens array 34 is positioned on the straightline 23 corresponding to each lens 11. Therefore, appropriate opticalperformance can be achieved regardless of changes in ambienttemperature.

The present invention is not limited to the above-described embodiments.Various modifications can be made as required.

For example, according to the above-described embodiments, the opticalfiber 19 is disposed as the optical device on the light-exiting side ofthe lens array 8. However, the present invention is not limited to aconfiguration such as this. For example, instead of the optical fiber19, a light-receiving device, such as a photodetector, including aplurality of light-receiving elements corresponding with the lenses 11can be disposed. Even in an instance such as this, optical couplingefficiency between the light-emitting device 10 and the light-receivingdevice can be favorably maintained. The light-emitting device can alsobe a device in which the light-emitting elements are formed in an array,other than the VCSEL 16.

The main components of the present invention can be applied to anoptical device other than the lens array apparatus, such as an opticaldevice including a lens and a light-emitting device disposed in aposition facing the lens in the thickness direction. A light-emittingelement is formed in the light-emitting device from which light isemitted towards the lens. In other words, an optical device such as thiscan be configured such that, as a predetermined angle of gradient inrelation to the thickness direction, the exiting direction of light fromthe lens is at an angle of gradient allowing the converging point of thelight emitted from the lens to be positioned on a predetermined straightline that is parallel with the thickness direction, under a plurality ofdifferent ambient temperatures. As a result, in a manner similar to thatof the lens array apparatus, appropriate optical performance can beachieved regardless of changes in ambient temperature.

1. A lens array apparatus comprising: a lens array including a pluralityof lenses formed such as to he arrayed in a predetermined arraydirection and formed to have a predetermined thickness in a thicknessdirection that is perpendicular to the array direction, that emits lightthat has entered the plurality of lenses and corresponds to each lensfrom each lens towards a predetermined converging point; and alight-emitting device that is disposed in a position facing the lensarray in the thickness direction and on which a plurality oflight-emitting elements of a same number as a number of lenses areformed, the light-emitting elements respectively emitting lightcorresponding to each lens towards the plurality of lenses, wherein as apredetermined angle of gradient in relation to the thickness directionfor each lens, an exiting direction of light from each of the pluralityof lenses is at an angle of gradient allowing a converging point of thelight emitted from each lens to be positioned on a predeterminedstraight line that corresponds to each lens and is parallel in thethickness direction, under a plurality of different ambienttemperatures.
 2. The lens array apparatus according to claim 1, whereineach center axis of the plurality of lenses is formed parallel with thethickness direction, and the exiting direction is at the angle ofgradient by the plurality of light-emitting elements being formed suchas to be displaced by a predetermined displacement amount in the arraydirection from each center axis of the plurality of lenses.
 3. The lensarray apparatus according to claim 1, wherein each of the plurality oflenses has a lens surface on a light-entering side facing thelight-emitting element and a lens surface on a light-exiting sideopposing the lens surface on the light-entering side, and the exitingdirection is at the angle of gradient by each of the plurality of lensesbeing formed such that a predetermined displacement amount in the arraydirection is present between a center axis of the lens surface on thelight-entering side and a center axis of the lens surface on thelight-exiting side.
 4. The lens array apparatus according to claim 1,wherein the exiting direction is at the angle of gradient by each centeraxis of the plurality of lenses being formed at the angle of gradient inrelation to the thickness direction.
 5. The lens array apparatusaccording to claim 1, wherein a light-receiving device is disposed in aposition on a light-exiting side of the lens array, the light-exitingside being a side from which light from the plurality of lenses exits,the light-receiving device including a plurality of optical fibers of asame number as a number of lenses into which light emitted from eachlens respectively enters or a plurality of light-receiving elements of asame number as a number of lenses receiving light emitted from eachlens.
 6. (canceled)
 7. (canceled)
 8. (canceled)
 9. (canceled) 10.(canceled)
 11. (canceled)
 12. (canceled)
 13. (canceled)
 14. The lensarray apparatus according to claim 2, wherein a light-receiving deviceis disposed in a position on a light-exiting side of the lens array, thelight-exiting side being a side from which light from the plurality oflenses exits, the light-receiving device including a plurality ofoptical fibers of a same number as a number of lenses into which lightemitted from each lens respectively enters or a plurality oflight-receiving elements of a same number as a number of lensesreceiving light emitted from each lens.
 15. The lens array apparatusaccording to claim 3, wherein a light-receiving device is disposed in aposition on a light-exiting side of the lens array, the light-exitingside being a side from which light from the plurality of lenses exits,the light-receiving device including a plurality of optical fibers of asame number as a number of lenses into which light emitted from eachlens respectively enters or a plurality of light-receiving elements of asame number as a number of lenses receiving light emitted from eachlens.
 16. The lens array apparatus according to claim 4, wherein alight-receiving device is disposed in a position on a light-exiting sideof the lens array, the light-exiting side being a side from which lightfrom the plurality of lenses exits, the light-receiving device includinga plurality of optical fibers of a same number as a number of lensesinto which light emitted from each lens respectively enters or aplurality of light-receiving elements of a same number as a number oflenses receiving light emitted from each lens.